How your baby's growing: This week, your baby measures over 16 inches long. He weighs about 3.3 pounds (try carrying four navel oranges) and is heading into a growth spurt. He can turn his head from side to side, and his arms, legs, and body are beginning to plump out as needed fat accumulates underneath his skin. He's probably moving a lot, too, so you may have trouble sleeping because your baby's kicks and somersaults keep you up. Take comfort: All this moving is a sign that your baby is active and healthy.

How your baby's growing: Your baby's about 15.7 inches long now, and he weighs almost 3 pounds (like a head of cabbage). A pint and a half of amniotic fluid surrounds him, but that volume will decrease as he gets bigger and takes up more room in your uterus. His eyesight continues to develop, though it's not very keen; even after he's born, he'll keep his eyes closed for a good part of the day. When he does open them, he'll respond to changes in light but will have 20/400 vision — which means he can only make out objects a few inches from his face. (Normal adult vision is 20/20.)

See what your baby looks like this week.

How your baby's growing: Your baby now weighs about 2 1/2 pounds (like a butternut squash) and is a tad over 15 inches long from head to heel. His muscles and lungs are continuing to mature, and his head is growing bigger to make room for his developing brain. To meet his increasing nutritional demands, you'll need plenty of protein, vitamins C, folic acid, and iron. And because his bones are soaking up lots of calcium, be sure to drink your milk (or find another good source of calcium, such as cheese, yogurt, or enriched orange juice). This trimester, about 250 milligrams of calcium are deposited in your baby's hardening skeleton each day.

See what your baby looks like this week.

How your baby's growing: By this week, your baby weighs two and a quarter pounds (like a Chinese cabbage) and measures 14.8 inches from the top of his head to his heels. He can blink his eyes, which now sport lashes. With his eyesight developing, he may be able to see the light that filters in through your womb. He's also developing billions of neurons in his brain and adding more body fat in preparation for life in the outside world.

See what your baby looks like this week.